Drives are control devices that are employed to control, monitor and/or otherwise interact with a variety of operational characteristics and parameters of motors such as, for example, motor speed, motor torque, motor power usage, etc. A wide variety of drives are available for use in conjunction with a wide variety of types of motors, including both alternating current (AC) motors such as synchronous motors and induction motors, and also direct current (DC) motors. Drives can also be used to control, monitor, or otherwise interact with a variety of other electromechanical machines such as generators and motor/generator hybrids (or even other types of machines and/or processes).
The control provided by drives includes the direct control over the power flow to the controlled motors or machines. Many drives are pulse width modulated (PWM) drives that rapidly turn on and off the flow of current (and the voltages) applied to the motors being controlled. In some circumstances, power that is effectively AC (including, for example, three-phase AC) can be provided to a motor simply by switching on and off DC sources with respect to the motor in an appropriate time-varying manner. Often, such PWM drives include a circuit board with a controller (e.g., a computer, microprocessor or programmable logic device (PLD)) and an array of controllable power switching devices such as power transistors that are switched on and off by the control device.
Drives can be used to control motors of a variety of different power levels. A medium voltage AC drive, for example, generally is understood to be a drive used to control an AC motor requiring input voltages within the range of about 2400 to 7200 Volts AC. Exemplary medium voltage AC drives include, for example, the Allen-Bradley PowerFlex 7000 family of drives manufactured by Rockwell Automation, Inc. of Milwaukee, Wis., the beneficial assignee of the present application. In contrast, a low voltage AC drive typically would be used to control an AC motor requiring input voltages at lower levels (e.g., 480 Volts AC), while a high voltage AC drive would be used to control an AC motor requiring input voltages at higher levels (e.g., 10,000 Volts AC). Drives can likewise be configured for operation with other types of motors and other machines that are intended to operate at a variety of different power levels or require a variety of different power characteristics.
It is usually only possible for human beings (or other entities, e.g., computers) to interact with conventional drives in limited manners and/or within restricted environments. For example, in industrial environments, it is often only possible for human beings (e.g., technicians or other personnel who are operating or monitoring a manufacturing process) to control and/or monitor the operation of drives in an indirect manner by way of signals communicated via intermediate devices. Various different types of intermediate devices are possible. For example, the speed of a drive can be controlled by a speed potentiometer connected to an analog input of the drive and manually adjusted by the operator, while starting and stopping of the drive can be controlled through the use of hardwired pushbuttons for Start and Stop. Also, in some circumstances, specialized control terminals with specialized graphical user interfaces (GUIs) allow operators to access drives to which those control terminals are in communication.
Nevertheless, to the extent that drives are accessible by human beings (or other entities) by way of such intermediate devices, the manner of access is often constrained by the requirements of those intermediate devices. For example, in circumstances where access to drives is made possible by way of specialized control terminals with specialized GUIs, interaction via such control terminals/GUIs often requires the installation and use of special proprietary hardware and/or software at the locations of the operating personnel, for example, a PanelView 550 Monochrome Terminal available from Rockwell Automation equipped with appropriate firmware. Also, to the extent that such control terminals/GUIs require software (particularly firmware), such software often is only appropriate for use with a given terminal/GUI and is not transferable to other terminals/GUIs. This is the case even where a control terminal is capable of receiving information from a drive via a standardized type of connection such as an Ethernet connection.
Additionally, even where specialized control terminals/GUIs are employed in conjunction with drives to facilitate the accessing of the drives, such access is usually limited in terms of the rapidity with which desired information can be obtained from the drives and/or the rapidity with which commands or other information can be provided to the drives. The coupling of such control terminals/GUIs to drives typically involves the use of one or more intermediary hardware coupling components connected in between the terminals/GUIs and the drives. Also, the communication of signals between the control terminals/GUIs and the drives typically requires the addition and removal of protocol information in relation to the signals. Both the interposition of intermediary components and the addition/removal of protocol information slow down the rate at which information can be communicated between the control terminals/GUIs and the drives.
Further, because special proprietary hardware and/or software is typically required to allow persons to interact with drives by way of such control terminals/GUIs, and because such hardware and/or software is separate from (albeit directly or indirectly coupled to) the hardware and/or software implemented on the drives themselves, changes to aspects or features of the drives often necessitate changes in the hardware and/or software allowing accessing of the drives. If appropriate changes to the accessing hardware/software are not made, compatibility problems can result. Yet configuring/upgrading of the hardware and/or software (e.g., firmware) on a control terminal separate and/or remote from a drive often is burdensome and costly, as it typically requires a technician to visit the control terminal and install software onto and/or otherwise modify or reconfigure the control terminal. While configuring/upgrading of a drive typically necessitates configuring/upgrading of the control terminal, typically the configuring/upgrading of the two devices cannot be performed in a coordinated manner, e.g., supply by performing a single action or process or with a single package.
In addition to providing access to motor drives in the aforementioned manners, it is also known (particularly in industrial environments) to provide access to motor drives via programmable logic controllers (PLCs) that are in communication with the drives. In recent years, PLC devices having both PLCs and accompanying web servers (e.g., “web-enabled PLCs”) have been developed allowing users to access, via the Internet, both the PLCs as well as devices coupled to the PLCs such as motor drives. However, the access to motor drives afforded by such web-enabled PLCs is disadvantageous for several reasons. First, while configuring/upgrading of a drive typically necessitates configuring/upgrading of software or other information on the web-enabled PLC, such configuring/upgrading of both devices typically cannot be performed in a coordinated manner, e.g., simply by performing a single action or process or with a single package.
Further, communication of any data between the drives and the web servers (and thus between drives and users on the Internet) is restricted by the processing/transmission efficiency of the PLCs themselves, which are situated between the web servers and the drives. Communication between the web servers and the drives also is restricted insofar as typically the signals sent to and received from the drives by the PLCs are communicated by way of any one of a number of proprietary intermediary devices including, for example, backplanes associated with the PLCs and various signal processing devices. The operation of such intermediary devices typically restricts the types of information that can be communicated, and considerably slows down the speed with which information can be communicated between the drives and PLCs, thus limiting the volume of information that can be transmitted effectively in a given time period. In some cases, communication adapters or converters are often coupled in between the PLCs and the drives, further restricting the types of information that can be communicated and reducing the speed of communication. For at least these reasons, web-enabled PLCs do not resolve the aforementioned problems associated with providing access to drives.
Although additional systems also exist that include web servers in association with other devices (e.g., other than PLCs), it is unclear whether such additional systems might be capable of providing improved access to drives. As in the case of web-enabled PLCs, a number of such systems employ web servers that are in communication with other devices by way of backplanes, backplane drivers and/or other intermediary devices. Consequently, communications between the web servers and other devices are typically delayed or restricted in various manners, such that any information to be communicated to and from those other devices by way of the web servers also tends to be delayed or restricted in various manners. Thus, as in the case of many of the other above-described systems, it would appear that it still would be difficult to configure or upgrade both a drive and associated web server in a coordinated, efficient manner.
Given the ubiquity of drives for controlling motors, other electromechanical machines and other machines in many environments including (but not limited to) industrial environments, and given the above-described limitations associated with controlling, monitoring and otherwise interacting with such drives as they are conventionally implemented, it would be desirable if an improved drive/drive system could be developed that would overcome one or more of these limitations. For example, it would be desirable if an improved drive system could be developed that in at least some embodiments provided enhanced access in terms of communication with other systems or entities (and/or operators or other personnel). More particularly, it would be desirable if an improved drive system in at least some such embodiments allowed for enhanced communication of commands and other information to and/or from the drive system, such that the speed of communicating information/commands to and from the drive system was not as significantly reduced due to the presence of intermediary hardware components and/or the addition/removal of communication protocol information as in conventional systems such as those discussed above.
Also for example, it would be desirable if an improved drive system could be developed that in at least some embodiments was accessible without the need for installing significant specially-designed or proprietary hardware (e.g., a specialized control terminal) or software at the location of the person or entity desiring access. Indeed, it would be further desirable if such an improved drive system could be developed that allowed access at multiple locations without the installation of different specially-configured hardware and/or software at those various locations. Additionally, it would be desirable if such an improved drive system could be developed that in at least some embodiments eliminated or reduced the possibility of incompatibilities arising between the drives and the access terminals/devices despite the upgrading or other modification of the drives, and alleviated some of the costs associated with configuring, upgrading or other modification of the drives.